import java.util.Scanner;

public class Test04 {
    public static void main(String[] args) {
        int a,b,c;
        Scanner scanner = new Scanner(System.in);
        c = scanner.nextInt();
        int max = Integer.MIN_VALUE;
        for (b = c /3 ; b <= Math.sqrt(c) ; b++) {
            a = c -b;
            max = Math.max(max,b*a);
        }
        System.out.println(max);
    }
}
